Rolling liquid droplets are of great interest for various applications including self-cleaning of surfaces. Interfacial resistance, in terms of pinning and shear rate, has a critical role in droplet rolling dynamics on hydrophobic surfaces. Lowering the interfacial resistance requires reducing the droplet wetting length and droplet fluid contact area on hydrophobic surfaces. The present study examines droplet rolling behavior on inclined hydrophobized metallic meshes, which facilitate reduced wetting length and contact area of droplets. Experiments are carried out using a high-speed recording facility to evaluate droplet translational and rolling velocities over various sizes of hydrophobized meshes. The flow field inside the droplet fluid is simulated in 3-dimensional space mimicking the conditions of experiments. The findings reveal that droplet translational velocity attains significantly higher values for hydrophobized meshes than plain hydrophobized metallic surfaces. Increasing the mesh size enhances the droplet velocity and reduces the droplet kinetic energy dissipation created by interfacial surface tension and shear forces. Increasing the droplet volume enhances the droplet velocity despite the fact that pinning and frictional forces increase at the liquid–mesh interface. Hence, for rolling droplets on the mesh surface, the increase in the gravitational force component becomes larger than the increase in interfacial pinning and frictional forces.

中文翻译：

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疏水化金属网可以缓解水滴滚动

滚动液滴对包括表面自清洁在内的各种应用具有重要意义。就钉扎和剪切速率而言，界面阻力在疏水表面上的液滴滚动动力学中具有关键作用。降低界面电阻需要减少疏水表面上的液滴润湿长度和液滴流体接触面积。本研究研究了倾斜疏水化金属网上的液滴滚动行为，这有助于减少液滴的润湿长度和接触面积。使用高速记录设备进行实验以评估液滴在各种尺寸的疏水化网格上的平移和滚动速度。在模拟实验条件的 3 维空间中模拟液滴流体内部的流场。研究结果表明，与普通疏水化金属表面相比，疏水化网格的液滴平移速度显着更高。增加网格尺寸可提高液滴速度并减少由界面表面张力和剪切力产生的液滴动能耗散。尽管在液体-网格界面处钉扎力和摩擦力增加，但增加液滴体积会提高液滴速度。因此，对于在网格表面滚动液滴，重力分量的增加变得大于界面钉扎力和摩擦力的增加。增加网格尺寸可提高液滴速度并减少由界面表面张力和剪切力产生的液滴动能耗散。尽管在液体-网格界面处钉扎力和摩擦力增加，但增加液滴体积会提高液滴速度。因此，对于在网格表面滚动液滴，重力分量的增加变得大于界面钉扎力和摩擦力的增加。增加网格尺寸可提高液滴速度并减少由界面表面张力和剪切力产生的液滴动能耗散。尽管在液体-网格界面处钉扎力和摩擦力增加，但增加液滴体积会提高液滴速度。因此，对于在网格表面滚动液滴，重力分量的增加变得大于界面钉扎力和摩擦力的增加。